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ANNULAR S LAR ECLIPSE AT THE CORE
An active region on the sun with dark sunspots. Image credit: NASA/SDO/AIA/HMI/Goddard Space Flight Center
will stop producing energy. At that stage, the Sun will start to swell, cool and will expand to become a huge red giant. At that time, the size of the Sun will increase by about two and a half times that of today, engulfing planets up to Venus and maybe even Earth. After that it will start shrinking again, turning atoms of helium into more massive atoms like carbon and oxygen. But with Sun’s mass, the process cannot go any further and a stage will come when all reactions will stop. The newly formed elements will collect at the centre of the Sun, which will then shed most of its red giant envelope – creating a planetary nebula and leave behind a hot white dwarf star as remnant. The Sun has existed for about five billion years and will last for another five billion years.
Space weather caused by the Sun
In addition to light and heat, the Sun gives out electromagnetic radiation of other wavelengths. These wavelengths include radio waves, ultraviolet rays, high energy X-rays, etc. The Sun also emits streams of charged particles commonly known as solar wind. Explosive events like solar flares and coronal mass ejections (CMEs) cause violent release of gas and magnetic fields at the Sun’s surface, which send solar storms into space. Some of the energetic particles of these storms are deflected by the Earth’s magnetosphere. When the energetic particles collide with the atoms in the Earth’s upper atmosphere, it
creates a natural display of light called aurora. Auroras are the most visible effect of the Sun's activity on Earth's atmosphere. To observe space weather events, scientists use different instruments like land- and space-based sensors and imaging systems to view the activity at various depths in the solar atmosphere.
Observation of the Sun
Events like solar eclipse are very rare. They are natural phenomena which are well understood scientifically. Many important scientific observations related to the Sun can only be carried out during such occurrence. On normal days, many features and phenomena of the Sun cannot be studied due to the brilliance and high luminosity of the Sun. During a solar eclipse, when the Sun is covered by the Moon, the outer layers of the Sun become visible. It gives a window of opportunity to the scientists to study more about the Sun. Today, we know several important facts about the Sun but many phenomena like physical and dynamic processes inside the solar corona, the sharp increase in temperature in the corona region, the magnetic field of the Sun and sunspot, etc., are yet to be understood completely.
The author is Scientist ‘F’ in Vigyan Prasar. Email: kapil@vigyanprasar.gov.in
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